Firefighters across the country this past weekend honored the first responders who died in the 9/11 terrorist attacks with a series of grueling tributes.

Stair climbs, in which firefighters climb the equivalent of the World Trade Center, take place each year near the anniversary of the attacks.

This past weekend, firefighters from coast to coast did their part to remember the 343 firefighters and rescue workers who made the ultimate sacrifice at the World Trade Center, and they also did their best to understand the physical challenges the heroes went through.

There also will be stair climbs Wednesday, the 12th anniversary of the terrorist attacks, and still more this coming weekend. Money raised at the events goes toward the National Fallen Firefighters Foundation.

In San Diego, firefighters, police, enlisted men and women, and regular civilians climbed the stairs of the Hilton San Diego Bayfront hotel. Some wore regular clothes, others wore roughly 60 pounds of gear.

In Nashville, firefighters from surrounding areas gathered at the Tennessee Tower to climb and descend the building's 24 flights of stairs four separate times. Dickson firefighter John Davis told the Tennessean that he climbs in memory of FDNY Capt. Thomas Haskell Jr.

“There are times when I thought I wasn’t going to do it either,” Davis told the Tennessean. “But I take a look at the guy on the lanyard on my neck and think, ‘This is for him.’"